The study has not shown what the submission or the study says it shows. What it shows is that when separated into two groups, women who self identify as women and those who don't, the two groups have their submissions pulled at different rates.
There is nothing in the study to show that the two groups are comparable in their ability to code. Another way to look at the numbers in the study would be to say that women who self identify as women are not as good at coding as those who don't. Both statements are equally invalid, the study doesn't show either.